Property:Monitoring surveys and results
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R
In September 2015, section one of the river was completely dry, but following the creation of the low flow channel, in September 2016 there was still 1ft of water retained within that section.
Before the works were completed, a water vole survey carried out in 2015 only found old unused burrows, with no signs of water voles. In 2016 another water vole survey was carried out, detecting 12 feeding stations and four latrines.
In 2015 section two was completely uniform with no pools or any habitat features. Following the work, 22 berms were constructed providing cover for fish and providing deeper areas that would help maintain the depth during low flow periods. Planting was successful, and in time, the vegetation will grow and create a natural meandering flow. +
U
In addition to the established annual fish monitoring programme downstream of Easton Walled Garden and invertebrate sampling at Easton Lane Bridge, visual inspections of the enhanced reach will be undertaken, and the fixed point photographic record will be updated to monitor the integrity and performance of the in-stream enhancements and record any changes they are making to river morphology. Post-works redd (trout spawning nest) surveys were undertaken upstream and downstream of Easton Lane. 6 redds were located in the upstream (Easton Park) section, but none were located downstream. These surveys provide a baseline for future monitoring. +
B
In additon to the usual measurement of hydrological, biological, and physical-chemical quality elements, chemical measurements were also taken. The stream was strongly polluted prior to the measures. Therefore, concentrations of heavy metals, micropollutants and pesticides were monitored. +
L
In order to validate these actions and evaluate the results, the project carried out a comprehensive monitoring program including biological, physical-chemical and hydromorphological indicators. This facilitated the subsequent transfer to the rest of the basin and other rivers with similar problems.
Monitoting actions were focused on :
+ Operation indicators at fish passage systems
+ Fish community and populations
+ Bird community and riverbanks associated fauna
+ Spatio-temporal dynamics of vegetation communities in the restored areas
+ Ecological status of water bodies and sediment monitoring in each weir +
In progress. The environmental characteristics of the site are determined, above all, by the presence of many habits. Three of these are targeted by the project: 1150* “Coastal Lagoons”, 1510 “Mediterranean salt steppes”, 2270*. Wooded Dunes with Pinus pinea and/ or Pinus pinaster and sites which are suitable for the restoration of habitat 2250*, Coastal Dunes with Juniperus spp.”
The project activities will be carried out in the SCI “Capitanata wetlands” (IT9110005) and in the SPA “Marshes in the Gulf of Manfredonia” (IT9110007). The mosaic of habitats in the project area renders the site especially suitable for the presence of numerous animal species invertebrates, fish, amphibians, reptiles, birds and mammals) of significant conservation interest. The added value of the project lies in increasing the availability of suitable habitats for the nesting, overwintering and resting during migration of birds through environmental restoration works. These works make a significant contribution to the recovery of wetland environments in Southern Italy. +
H
In recent years there has been extensive monitoring and evaluation of wetland sites. An independent review by the River Restoration Centre and Jonathan Cox Associates was commissioned in 2015 which evaluated eight sites that had previously been restored. The findings of this review recommended an expanded monitoring programme. In 2016 we developed a Monitoring Strategy and Delivery Plan. This details what evidence should be collected at future wetland restoration sites in the NF.
Since 2014 monitoring and surveys have been undertaken including:
• pre and post work fish population surveys
• invertebrate surveys and fish spawning surveys
• river habitat surveys and modular river physical surveys
• time-lapse photography
• botanical surveys
• fixed point photography
• Riverfly monitoring by volunteers
• water level and quality monitoring.
Alongside the restoration monitoring, species surveys have been undertaken. Whilst it is important to monitor direct impacts of the work using the methods described above, the real aim of the restoration is to increase the resilience of the habitats that are unique in the New Forest long into the future. Therefore, these species surveys are an important indicator of the health of these habitats. +
B
In the beginning of the project the stream discharge was too low, so that sludge and leaves piled up in the bed. This caused a high biological oxygen demand and consequently a low oxygen level. As the project developed, a continuous vegetation cover developed, making mowing unnecessary. Black alder and hazel proved especially suitable, since they grow fast. Oxygen levels have become more stable and nutrient runoff into the stream has decreased. +
W
In the framework of the network of demonstration
sites, the Water agency established a monitoring
programme before and for five years (n+5) after
the works, addressing biological aspects (fish, macroinvertebrates,
diatoms) and the hydromorphology.
This programme was filled out with a complete
survey of active and potential redds for trout, in
the main channel and in the reconnected secondary
channels. This survey was carried out by the Onema
local office*.
A multi-partner monitoring plan (CLEDA, Water
agency, Onema, Hautes-Alpes department, IRSTEA,
Écrins national park, consulting firms) has been set
up to complement the EU ALPeril programme that
made possible Lidar topographical surveys in 2009
and 2015.
In addition, a thesis organised by Onema/CNRS/
University of Paris 7 is now under way to assess the
effectiveness of restoration works on rivers characterised
by high levels of sediment transport and to
study the dynamics of sediment transport.
Even in the absence of a significant flood, the entire
widened section of the active channel has since
become a braided riverbed. The current monitoring
programme will provide information on the subsequent
changes in the reloaded zone.
The works produced a long-lasting solution for the
problems arising from riverbed scouring and resolved
the difficulties threatening the attractiveness
of the valley for tourists (safeguarding the Champsaur
Lake, creation of a walking trail along the Drac,
passage for white-water craft, enhanced fishing conditions,
etc.).
From the ecological standpoint, sediment reloading
of the Drac and the rise in groundwater reconnected
six tributaries and resupplied with water side channels
of high biological value. The return to the Drac
of emblematic species, such as the common kingfisher,
was observed shortly after the works. The living
and reproductive zones of aquatic species that had
abandoned the most heavily down-cut areas were
recreated and clogging of the riverbed was reduced.
During the 2015-2016 winter, Onema noted approximately
30 salmonid redds over the four-kilometre
work area where only five had been observed prior
to the works.
The physical restoration of the Drac required enormous
resources and means at a very high cost. The
project would have been much smaller and less expensive
if measures had been taken when riverbed
incision was first observed.
C
Increasing the diversity of the channel provide different habitats to support a wider diversity of plants and animals. Fish bays provide shallow, slower flowing, warmer water preferred by small fish and fry.
Blackwater habitats increase habitat diversity, whilst providing a refuge for fish and invertebrates from high flows.
The banks and channel of the main river were re-profiled at 9 locations. The river bank was lowered to re-connect the river to its natural floodplain, improving marginal and riparian wetland habitats. Improving connectivity between the river and floodplain allows sediment to settle out on the floodplain, and fish and invertebrates to escape from the highest flows in flood events By storing water on the floodplain sooner, downstream flood risk can also be reduced. The bank material was pushed into the channel, creating earth berms. These narrow the channel during low flows, increasing water velocity. This helps other river processes such as sediment transfer, erosion and depositing and oxygenation of the water, which creates habitats and improves water quality. The berms also create diversity of marginal and aquatic habitats, which was previously very uniform. In addition, shallow bays were created and a backwater improved to provide additional habitat for fish and fry. +
L
Individual NFM features have been monitored using time lapse photography to show how they function during high flows and show how the locations of the work recover and develop. Additional monitoring is ongoing to assess the impacts of NFM measures on suspended sediment concentrations regarding the bunds installed. Two turbidity sondes (one upstream and one downstream) have been installed to achieve this and assess the cumulative impact of the catchment-wide features.
Monitoring is continuing into 2020. Initial results indicate a reduction of sediment within the watercourse downstream of the floodplain reconnection. During peak flow the interventions are slowing the flow, pushing water onto the floodplain and reducing peak levels. +
T
Initial electro-fish survey on Thackthwaite beck prior to levee removal. Results showed low numbers of Salmonids and large numbers of Minnows. This is to be expected as prior to the levee removal the beck was very canalised and could not retain finer material suitable for spawning fish.
Redd counts in autumn to monitor Trout and Salmon spawning success. 2023 was the best year to date for the number of redds, and sightings of Sea Trout and Salmon.
Water quality sondes have been installed by the Environment Agency, these monitor water quality, temperature and turbidity. +
B
Installation of floating islands, Maintenance and revegetation of swamp banks, installation of observatories, maintenance of crops for bird alimentation. As a result, new species have arrived and the population of Ardeola ralloides is increasing. +
E
Integrated and science-based monitoring has illustrated positive change over the course of the project. Baseline geomorphology, ecology, and water chemistry surveying and repeat surveys during construction within and adjacent to the scheme footprint have enabled the design of the scheme to progress in a way which protects the existing characteristics of the area.</p>
<p>The scheme monitoring includes:<br>
• Geomorphological surveys identified areas where bank protection was required and on-going monitoring will be undertaken to ensure that erosion is mitigated.<br>
• Water chemistry sampling has proven that the water treatment feature has been successful in removing dieldrin from the Tyock Burn.<br>
• Continued monitoring of the newly established areas of wetland, riparian and wildflower meadow planting will be required to ensure that these biodiverse habitats flourish.<br>
• Large areas of giant hogweed and Japanese knotweed have been treated over the past seven years. On-going monitoring and action will be required to ensure that these do not return to the area.<br>
• Bat and bird boxes will continue to be monitored and maintained as required.<br>
• Aerial surveys will continue into the future to undertake wide scale assessments. +
H
Invertebrate monitoring prior to work found only worms and leeches. Freshwater shrimp and blackfly larvae colonised very rapidly and a few months later mayfly larvae, caddis larvae and water beetles were also present. +
B
Invertebrate within the wet habitats of the brook valley responded positively to the restoration. There was an increase in diversity following the works.
The stream provided flood storage during the 2001 flooding. +
R
It is expected that the project will improve the conditions of the biodiversity in the restored area, contributing to halting the loss of biodiversity. +
S
Shaping and protecting water-mud biotopes in Garwolin Forest division through development of small retention +
It is hard to evaluate how the implemented investments contributed to flood protection. However, it is beyond
doubt that the investments increased the groundwater level, and increased the soil humidity. Today, less water flows out from the forest areas. The implemented measures thus caused significant ecological effects,
especially:
• restoration and maintenance of flora biotopes and animals connected with aquatic and wetlands
environments;
• appearance of endangered fauna species;
• diversification of the migration trails of migrating birds in the vicinity of the Vistula valley;
• the damming devices fulfil various ecological functions such as functioning as watering holes for animals,
feeding sites, breeding and rest sites for birds;
• restoration and maintenance of the biotopes of many species of fauna important to the EU e.g. fire –
bellied toad, crested newt, black stork, white – tailed eagle, crane, kingfisher, European beaver, otter. +
W
Kick Sampling - PSSI, BMWP, ASPT
Fixed Point Photography
River Corridor Surveys
The data which has been collected as part of this project has been the most rigorous of any Wyre Rivers Trust project that has been delivered to date. By engaging the services of two students from Lancaster University we have been able to deliver a considerable of pre project delivery monitoring and we expect that we will be able to engage another student when the project has been delivered therefore allowing us to evaluate the success of our project over the next year. The majority of the data which has been recorded is invertebrate data which has collected using kick sampling, this has been analysed and various indices have been used to interpret it. We were also fortunate to have the use of two Environment Agency SONDES which were installed in June 2015, this data has been recorded and we hope to be able to compare it to SONDE data which will be collected in the summer of 2016. Further to this we have also collected river corridor data and undertaken fixed point photography which will allow us to compare the changes to the watercourse after a season of growth. +
D
La réalisation de l’état initial et la mise en
place des suivis après effacement s’intègrent
dans une démarche d’évaluation globale des
impacts des actions mis en œuvre au cours du
plan de gestion. Cinq stations réparties sur le
bassin versant ont été sélectionnées. Les compartiments
des macroinvertébrés, des macrophytes
et des poissons ont été analysés lors de
l’état initial réalisé en 2008. Un premier suivi
intermédiaire a été réalisé en 2011, le prochain
est prévu en 2014. Le syndicat a par ailleurs
lancé une étude de modélisation de l’impact
hydraulique de l’aménagement des ouvrages
sur les champs d’expansion des crues en 2011.
Les vannes des ouvrages étant déjà levées
avant le démantèlement et ne bloquant pas le
transit des espèces et des sédiments, les gains
écologiques potentiels sont minimisés, d’autant
que les cinq stations de suivi écologique
ne sont pas situées à proximité des ouvrages
hydrauliques supprimés. Toutefois, l’objectif
d’amélioration hydraulique visé au départ a
été atteint, de même que celui de pérennisation
de la situation existante en termes de
continuité écologique. D’après une seconde
étude de l’impact des démantèlements sur les
inondations (V2R, 2011), la suppression des
ouvrages devrait permettre de diminuer signifi
cativement les débordements locaux. Depuis
les démantèlements, deux crues de plein bord
sont survenues : les zones comprenant des
habitations et auparavant inondées pour des
débits inférieurs ne l’ont pas été. L’Aa traversant
plusieurs villes, cette opération permet
donc de diminuer le risque d’inondation pour
les habitations riveraines du cours d’eau.
À l’avenir, le syndicat envisage la poursuite
des travaux engagés. Un barrage pourrait être aménagé par la création d’une rivière de
contournement au niveau d’un ouvrage hydraulique
doté d’une valeur patrimoniale. Par
ailleurs, six effacements d’ouvrages - dont l’un
est situé sur un site Natura 2000 - pourraient
être réalisés (dérasement ou arasement). Les
hauteurs de chute de ces ouvrages sont comprises
entre 0,8 et 3 m.
A
Le bureau d’étude choisi pour ce projet réalise,
l’année des travaux, un état initial portant sur les
invertébrés et les diatomées. Les protocoles utilisés
respectent la norme NF T90-350 pour l’indice biologique
global normalisé (IBGN) et la norme NF T90-
354 pour l’indice biologique diatomique (IBD).
Depuis la fin des travaux, la Fédération de pêche
d’Eure-et-Loir a effectué des pêches à l’électricité en
2009, 2011 et 2014 au droit de l’ancien ouvrage.
Depuis les travaux, on observe un décolmatage du
substrat, offrant des frayères potentielles pour la
truite fario. Une légère érosion du lit mineur est observée
juste après les travaux, elle semble s’être stabilisée,
ce qui peut être interprété comme l’atteinte
d’un certain « profil d’équilibre ».
Les pêches à l’électricité de 2011 et 2014 montrent une
amélioration de la structure du peuplement piscicole
dans l’ancienne zone ennoyée. On peut recenser sur la
station le chabot, le goujon, la loche franche, le vairon l’anguille, la lamproie de Planer et la truite fario. La
population de truite fario sur le secteur est composée
de 4 à 5 classes d’âge différentes, avec la présence de
truitelles sauvages (absentes en 2009), ce qui montre
qu’une reproduction a eu lieu sur la station ou à proximité.
Ceci a été permis par le rétablissement d’habitats
propices à la fraie dans l’emprise de l’ancien bief.
La suppression du vannage du moulin de Réveillon a
donc permis de rétablir la continuité écologique (piscicole
et sédimentaire) au droit de l’ancien ouvrage
sur environ quatre kilomètres.
Par mesure de précaution et en raison des contraintes
latérales fortes (présence d’une route et d’une zone
industrielle de part et d’autre du cours d’eau) les
actions sur les berges en amont de l’ouvrage sont
relativement lourdes. Plus de sinuosité pouvait être
donné au cours d’eau et les protections auraient pu
se limiter à la partie concave des sinuosités les plus
proches de la route et du grillage.
Bien que l’accès au site soit peu aisé, les riverains
manifestent néanmoins leur satisfaction face aux
résultats. Au vu de l’amélioration du peuplement
piscicole, les pêcheurs locaux montrent également
leur contentement vis-à-vis des travaux. De même,
déchargé des obligations d’entretien du vannage, le
propriétaire de l’ouvrage se déclare satisfait.
Sur les huit seuils ou barrages traités, aucun droit
d’eau n’est abrogé. La discussion avec les propriétaires
et l’obtention de compromis contribuent à la
réussite du projet. Aucune participation des riverains
n’est demandée, le syndicat estimant la restauration
de la continuité écologique d’intérêt général.